1. Field of the Invention
The present invention relates to a mounting structure for mounting a connector comprising a plurality of terminals on a circuit board.
2. Description of the Related Art
A connector generally comprises a connector housing comprising insulating materials and a plurality of terminals, which are arranged in the connector housing and composed of electrically conductive materials. The connector is mounted on the circuit board by soldering a tail part of the terminal to a predetermined position of the circuit board, and is electrically connected with a wiring pattern of the circuit board. Such a connector is electrically connected with other electronic appliances, parts or the like by incorporating a counterpart connector that fits into the connector, by being connected with a flat cable, a coaxial cable or the like, or in other ways.
As a method for soldering and fixing the connector to the circuit board, one of the most popular methods is a surface mounting type (a surface mount technology/method) and another is a dip type (a dipping method).
As for the surface mounting type, the tail part of the terminal of the connector is reflow-soldered to a predetermined position of the circuit board, that is, to a land part connected with the wiring pattern printed on the surface of the circuit board. On the other hand, as for the dip type, the other land part similar to the land part described above is prepared on the back surface of the circuit board, and a mounting hole for penetrating the circuit board is formed at the position of the land part. The tail part of the terminal of the connector is penetrated to the mounting hole from the front surface to the back surface of the circuit board, and the back surface of the circuit board is dipped in a dipping vessel (a dipping tub) where a fused solder is stored. Then, the terminal is soldered to the other land part.
When the surface mounting type and the dip type are compared, the advantageous point of the surface mounting type is as follows. That is, since it is not necessary to prepare the dipping vessel, it is easier and lower in cost than the dipping type. Further, in the dip type, since the mounting hole must be provided in the circuit board, the narrowed pitch between the terminals of the connector is limited to a pitch where the mounting holes do not make contact with each other. On the other hand, in the surface mounting type, since it is not necessary to provide the mounting hole in the circuit board, the pitch between the terminals can be easily narrowed, and thereby it is possible to promote the miniaturization of the connector, consequently, the miniaturization of the electrical appliance.
On the contrary, the advantageous point of the dip type is as follows. That is, in the surface mounting type, since only the tail part of the terminal is adhered to the surface of the circuit board by the solder, the contacting area is small, and it is difficult to satisfy the peeling strength from the circuit board. On the other hand, in the dip type, the terminal is penetrated to the back surface of the circuit board through the mounting hole, and is soldered under this condition. Thus, the contacting area is large, and the solder is penetrated into the mounting hole, so that the peeling strength is remarkably increased.
Therefore, for example, as disclosed in Japanese Patent Laid-Open Publication No. H11-251010 (laid-opened on 17 Sep., 1999), the surface mounting type is adopted when a connector has a comparatively small height and is used in the fields where a large stress is not generated at the time of connecting and disconnecting of a counterpart connector, a flat cable, a coaxial cable or the like, which is mounted on another electrical appliance or part. Conversely, the dip type is adopted, for example, when the connector has a comparatively tall height in the case where the large stress is generated at the time of connecting and disconnecting of the counterpart connector, or in the case where the connector is frequently connected and disconnected, as disclosed in Japanese Utility Model Registration No. 3047965 (published on 28 Apr., 1998).
In other words, when using the surface mounting type or using the dip type, both cases have had problems, which have been tolerated in the past. That is, when the surface mounting type is used, the pitch between the terminals can be narrowed, but the peeling strength is decreased. On the other hand, when the dip type is used, the peeling strength is increased, but the pitch between the terminals becomes large.
However, since today's market needs are matched with the background for miniaturization of electrical appliances, it is required that the mounting structure of a connector comprises a terminal having narrower and higher density pitches and an arrangement to be mounted on the circuit board at a small mounting area with the high peeling strength.